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Projects => Tech Help - Projects Page => Topic started by: LaceSensor on July 13, 2013, 12:06:44 PM

Title: Stage Fright over driving
Post by: LaceSensor on July 13, 2013, 12:06:44 PM
Hi

Built up the stage fright board today
Changes were the 30k resistors were 33k, and the 3k was 3.3k
Otherwise as stock

No matter where you set the trimmer this thing is clipping

Is this symptomatic of dodgy  LM13700s?
I had 4 and Ive tried the other in all permutations and I still get distortioin so I dont think its them
Ive tried other op amps, same.
Ive tried other transistors, same.
Reflowed all joints, same

I got everything from reputable sources.

thanks
Title: Re: Stage Fright over driving
Post by: jimilee on July 13, 2013, 03:10:22 PM
Nope, it sounds really good. Either there's a wrong component or bad ic's have you checked your voltages? I'd start at the jack just to see I the jack itself is screwy or a power supply is starting to go south on you.
Title: Re: Stage Fright over driving
Post by: Scruffie on July 13, 2013, 03:32:52 PM
Voltages.

The 13700 don't have that higher headroom and can go in to nasty distortion if pushed too hard, what pickups are you using?

That trimmer is less about 'biasing' as it is getting the correct current/wave out of the LFO, although with too higher current the OTAs do play worse.

Those 30k & 3k are in said current network and may make a difference...
Title: Re: Stage Fright over driving
Post by: LaceSensor on July 13, 2013, 03:45:49 PM
Quote from: Scruffie on July 13, 2013, 03:32:52 PM
Voltages.

The 13700 don't have that higher headroom and can go in to nasty distortion if pushed too hard, what pickups are you using?

That trimmer is less about 'biasing' as it is getting the correct current/wave out of the LFO, although with too higher current the OTAs do play worse.

Those 30k & 3k are in said current network and may make a difference...

Oh, jazzmaster p90 style or an electro acoustic...
Too hot an dbothered now will do later..

It's not the power supply or jack or any of that

I will change those resistors for the right value then...